On the Intensity Profile of Electric Lamps and Light Bulbs

We demonstrate that the time profile of the light intensity from domestic lighting sources exhibits simple yet interesting properties that foster lively student discussions. We monitor the light intensity of an industrial fluorescent lamp (also known as TL) and an incandescent bulb using a photodete...

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Bibliographic Details
Published inThe Physics teacher Vol. 51; no. 8; pp. 491 - 492
Main Authors Bacalla, Xavier, Salumbides, Edcel John
Format Journal Article
LanguageEnglish
Published American Association of Physics Teachers 01.11.2013
Subjects
Energy
Laboratory Equipment
Light
Physics
Science Instruction
Science Laboratories
Scientific Concepts
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Summary:We demonstrate that the time profile of the light intensity from domestic lighting sources exhibits simple yet interesting properties that foster lively student discussions. We monitor the light intensity of an industrial fluorescent lamp (also known as TL) and an incandescent bulb using a photodetector connected to an oscilloscope. The light intensity of these sources displays modulation at twice the ac power supply frequency. The familiarity of ac line power supply, commonplace light sources, and simplicity of the setup encourage student confidence, allowing them to think deeper and continually reassess their notions, and if managed can lead to a satisfactory explanation of the observations.
ISSN:0031-921X
DOI:10.1119/1.4824947